The technology of fluid film bearings is well established and used in many industries including aerospace, electronic semiconducting manufacturing, optics, machine tools and electrical power generation. Fluid film bearings typically use air or oil to create a frictionless separation force between two elements in motion relative to each other. The pressure of the fluid between the elements creates a separating force that creates a gap between the elements.
The gap filled with pressurized fluid acts like a positive stiffness spring, increasing its separation force, as the elements are forced together, for instance, by an outside disturbance. Unfortunately, the pressurized fluid cannot hold the element together if an outside force pulls the elements apart. Therefore, many fluid bearings comprise means to supply a preload force which acts to resist the separation of the elements. Preloading is typically accomplished by adding mass to one of the elements to supply a constant preload force which acts to force the element together. Unfortunately, the added mass also increases the inertia of the bearing which limits its dynamic response. Vacuum preloading, wherein a portion of the elements are pulled together by vacuum, can also be used to create a preload force. Vacuum systems offer only limited effectiveness and are unduly complicated. Preloading is also accomplished by using opposing fluid surfaces linked together by supporting structure. The present invention creates preload force by creating a magnetic force through the elements which acts to pull the elements together and increase dynamic response.